MRCP Revision Notes

Another random selection from MRCP Part 1 practice questions - normal updates will resume in May!

Treatment of Hyperlipidaemia - Elevated cholesterol and triglycerides are suggestive of remnant hyperlipidaemia. The most appropriate treatment in this case would be a fibrate. Statins are predominantly used to treat cholesterol. Nicotinic acid lowers cholesterol and triglycerides but it is poorly tolerated (primarily due to cutaneous flushing). Bile acid sequestrants reduce cholesterol but may actually increase triglyceride concentrations and are poorly tolerated. The effects of statins are usually maximal by about 4 weeks after an increase in dose. Fibrates in combination with statins are effective although there is a theoretical risk of myositis when used in combination. In a patient with high cholesterol not responding to a statin, ezetimib may be helpful. Ezetimib inhibits cholesterol absorption from the gut.

Resting Membrane Potential - The resting neurone is polarized (-ve on the inside, +ve on the outside). At rest, the cell membranes are less permeable to sodium than they are to potassium. The outside of the neurone is rich in sodium ions. When stimulated, the neurone permeability changes allowing sodium in and postassium out. The depolarization resulting from this movement causes the generation of an action potential.

Myelodysplastic Syndrome - This is characterised by peripheral cytopenia with marrow full of developing cells. Maturation is abnormal and there is reduced cell survival. It can initially be detected from the presence of abnormal red cell maturation (ie. a raised MCV) in the absence of other causes of anaemia. The most common presenting symptom is fatigue and this condition is far more common in the elderly population.

Rheumatic Fever & Differential - This condition affects children in the age 4-15 group as a result of Group A streptococcal infection. It is common in the middle east, eastern Europe and South America. The arthritis is classically a fleeting migratory polyarthritis affecting the large joints although isolated arthritis is the presenting symptom in 15-40% of cases. Differential diagnosis includes:

Still’s disease (arthritis is usually much more persistent in the affected joint)

Polyarticular juvenile idiopathic arthritis (small joints initially affected, no fever)

Childhood dermatomyositis (age 4-10, classic rash + muscle weakness)

Familial Mediterranean Fever - autosomal recessive in certain ethnic groups, characterised by recurrent attacks of fever, arthritis and serositis. Abdominal or chest pain due to peritonitis / pleurisy may occur.

Chagas Disease - This is a tropical parasitic disease caused by infection with the flagellate potozoan Trypanosoma cruzi. It is associated with sudden cardiac failure due to dilated cardiomyopathy. It is a protozoan parasite, known as the ‘kissing bug’. Patients are often asymptomatic for many years following infection but may develop cardiac failure. It is most prevalent in Central and South America and may cause mega-oesophagus and mega-colon as a complication.

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Acute Intermittent Porphyria - Does not typically result in skin manifestations but presents typically in a young woman admitted to hospital with severe abdominal pain, bilious vomiting and postural hypotension. AIP occurs due to the absence of porphobilinogen (PBG) deaminase and the combined oral contraceptive pill can precipitate an attack. Porphyria Cutanea Tarda on the other hand presents with a blistering skin rash on sun exposure, typically precipitated by alcohol.

Marfans Syndrome - This condition follows an autosomal dominant mode of inheritance and is caused by mutations in the fibrillin gene on chromosome 15. The diagnosis is made on clinical grounds. Major diagnostic criteria includes an early diastolic murmur, indicating aortic valve incompetence, likely to be secondary to aortic root dilatation requiring annual cardiology follow-up. Upwards lens dislocation (ectopia lentis) may be seen and minor criteria for diagnosis include arachnodactyly, minor valve prolapse and joint hypermobility.

Familial Hypocalciuric Hypercalcaemia - Is caused by a mutation of the calcium-receptor sensing gene leading to reduced calcium excretion and mild to moderate hypercalcaemia. Renal stones frequently occur in this condition and acute pancreatitis is rare. It is recommended that the patient maintains adequate hydration to reduce their risk of renal stones.

Sclerosing Cholangitis - Occurs classically in a patient with an inflammatory bowel disease. There is inflammation and fibrosis of the bile ducts with multiple areas of narrowing throughout the biliary system. The patient may be asymptomatic or may present with jaundice, pruritis and intermittent abdominal pain. There is a strong association with inflammatory bowel disease and men are more commonly affected than women.

Hodgkin's Lymphoma - The classic presentation is in a young woman presenting with weight loss and lymphadenopathy. Raised eosinophils in the full blood count are a strong clue towards the diagnosis and lymph node biopsy is necessary to confirm the diagnosis. Prognosis is related to clinical stage, bulk of tumour and histopathology. Presence of the 'Reed-Sternberg' Cell (with giant 'owls eye' nucleoli) are useful diagnostically.

IgA Nephropathy - This would typically occur in a young man who has repeated episodes of painless macroscopic haematuria following a upper respiratory tract infections. On a renal biopsy there will typically be diffuse mesangial proliferation and the condition results in chronic kidney disease in approximately 30% of cases. Heavy proteinuria, raised blood pressure and renal impairment are indicators of a poorer prognosis.